Japan's new prime minister, Yukio Hatoyama, has promised to make ambitious cuts in greenhouse gas emissions, months before world leaders meet for crucial climate change talks.
Hatoyama, who will take office next week, said Japan would seek to reduce CO2 emissions by 25% below 1990 levels by 2020, but said the target would be contingent on a deal involving all major emitters in Copenhagen in December.
"We can't stop climate change just by setting our own emissions target," he said at a forum in Tokyo. "Our nation will call on major countries around the world to set aggressive goals."
Hatoyama will discuss the initiative, which is far more ambitious than the equivalent 8% cut unveiled by the outgoing government in June, at a UN meeting on climate change in New York this month.
Connie Hedegaard, Denmark's minister for climate and energy, described the plan as a bold step forward. "For a long time, everybody has been waiting for everybody else to move in the negotiations. Japan has taken a bold step forward and set an ambitious target. I hope this will inspire other countries to follow suit."
The commitment places Japan firmly among countries committed to aggressive CO2 emissions cuts, despite mounting opposition from business and industry groups, which claim the measures will put jobs at risk.
"We have concerns about its feasibility in view of the impact on economic activities and employment, as well as the enormousness of the public burden," said Satoshi Aoki, the chairman of the Japan automobile manufacturers' association.
Harufumi Mochizuki, the outgoing vice minister of trade and industry, said Hatoyama had chosen a "very tough road ahead for the Japanese people and economy".
Hatoyama said his plan would create jobs in sectors such as renewables and manufacturing amid an expected rise in demand for solar energy, home renovations and energy-efficient cars and consumer electronics.
"There are cautious people who worry that it will hurt the economy and livelihoods, but I think it will change things for the better," he said.
To help achieve the reduction, Japan will create a domestic emissions trading market and introduce a "feed-in" tariff – financial rewards for industries that expand their use of renewable energy sources.
The Copenhagen talks will be dominated by attempts to persuade China, India and other big emerging economies to sign up to emissions targets.
Kim Carstensen, the head of the WWF's global climate initiative, said: "The decision by an important player such as Japan to do more and get serious about low carbon future can help break the deadlock between developed and developing countries.
"The climate negotiations are at a critical point and we need urgent progress to get a fair, ambitious and binding deal in Copenhagen."
The target brings Japan, the world's fifth-largest emitter of greenhouse gases, alongside the EU, which is committed to a 20% cut by 2020 from 1990 levels and 30% if other nations agree to match the target. But it is still at the lower end of the 25-40% cuts recommended by the UN climate change panel.
Hatoyama will have to reconcile his bold initiative with election pledges to eliminate road tolls and petrol surcharges.
As host of the Kyoto summit in 1997, Japan is keen to reposition itself at the forefront of the battle against climate change. Its emissions rose 2.3% in the year to March 2008, putting its 16% above its 2012 Kyoto target.
Yvo de Boer, the head of the UN climate change secretariat, said: "With such a target, Japan will take on the leadership role that industrialised countries have agreed to take in climate change abatement."